LeftClick on the little 'a' icon in the tray, or rightclick on it, and select the default 'On-Access Protection Control' entry.
Select the 'Details' view by clicking the 'Details...>>' button (unless you already see the details view, which has a '<< Less detail...' button')
On the details view, select the 'Internet Mail' icon in the toolbar at the left. Then select the 'Customize' button.
You'll find the 'Silent mode' on the 'Advanced' tab.
HTH
Doesn't work. (at least with general answer yes, have to wait for another virus to arrive to see what happens on general answer no)
....
avast! Antivirus: Inbound message INFECTED:
\product.doc.scr (Win32:Netsky-B [Wrm]) was (BEWARE!!!) left intact in the message., \product.zip (Win32:Netsky-B [Wrm]) was (BEWARE!!!) left intact in the message.
....
was left intact, not moved to the chest.
I had that working earlier but yesterday I made a fresh windows install and downloaded and installed newest version of avast and I just can't get it to move silently viruses to chest anymore.